Chloro-1,3-butadiene/alpha-alkyl acrylate ester-grafted copolymers

ABSTRACT

LOWER ALKYL AND CYCLOAKYL ESTERS OF UNBRANCHED C1-C4 ALKYLACRYLATES COPOLYMERIZE IN EMULSION WITH 2CHLORO-1,3-BUTADIENES UNTIL ALL THELATTER MONOMER IS EXHAUSTED, THEN GRAFT ONTO THE COPOLYMER BACKBONE SOFORMED. THE REACTION PROCEEDS IN TWO DISTINCT STEPS, THE GRAFTING STEP REGUIRING THE PRESENCE OF A POLYMERIZATION CATALYST, AN ANIONIC SURFACTANT,AND AT LEAST ONE CATION OF THE GROUP: TRIETHANOLAMMONIUM, TRI(2-PROPANOL) AMMONIUM, DIETHANOL-AMMONIUM, AND C1-C3 ALKYLDIETHANOLAMMONIUM. NOVEL GRAFTED COPOLYMERS OF 2-CHLORO-1,3BUTADIENES PRODUCED BY THIS PROCESS RANGE FROM RUBBERY TO PLASTIC MATERIALS. GRAFTED COPOLYMERS OF 2-CHLORO-1,3-BUTADIENES WITH METHYL METHACRYLATE ARE EXCELLENT ADHESIVES FOR PLASTICIZED POLYVINYL CHLORIDE.

April 17, 1973 y D. M. slMoNS CHLORO-l 3^BU'llaDIENE/d-ALKYL ACRYLATEESTER-GRAFTED COPOLYMERS Filed NOV.

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DON ALD M. S IMONS BY /QMW ATTORNEY United States Patent O ice 3728316Patented Apr. 17, 1973 3 728 316 It isonecessary, for satisfactoryreaction rates and consequen y high grafted copolymer yields, to carryout the CHLOR1,3BUTADIENE/oi-ALKYL ACRYLATE copolymerization in thepresence of an anionic surfactant ESTER-GRAFTED CUPLYMERS and of atleast one of the following cations:

Donald Max Simons, Wilmington, Del., assignor to E. I.

du Pont de Nemours and Company Wilmington Del. 5 Continuan'on-in-part ofapplicationSer. No. 836376, (a) methanolammomum (HOCHQCHMNE guneNZS,1969. This application Nov. 16, 1970, EH

er. 0.90112 b) t'2-- 1 I Int. Cl. COSE /26 t ri( piopano )ammonium CH3BGHZ aNH, U.S. Cl. 260-80.77 14 Claims 10 (c) dieihanoiammonium(Hoonionoiina or ABSTRACT 0F THE DISCLOSURE (d) aikyidieihanoiammouium(noomonmn Lower alkyl and cycloalkyl esters of unbranched i t CTC4aikyiacrylates copoiymerize in emulsion with 2 1 where R is an alkylradical having l-3 carbon atoms.

chloro-1,3-butadienes until all the latter monomer is ex- Such a cationusually is introduced as Part 0f the SUI" hansted, then graft onto thecopolymer backbone So factant used for emulsiiication, for example astriethanolformed` The reootion proceeds in two distinct Steps, theammonium dodecylbenzeriesulfonate; but it also can be grzitting stepreqniring the presence of a poiyinerization added as a salt of aconventional acid, for example as catalyst, an anionic surfactant, andat least one cation 2 tfie'fhanolanmolum C h10fde of the group:triethanoiammonintn, tri(2 ptopano1)ain The reaction is carried out inthe presence of a polymmonium, diethanol-ammonium, and C1-C3alkyldiethanolerlZa'Pn Catall/S; Preferably based 011 a redox pair.

ammonium Novel grafted copolymers of 2 Ch1oto 1,3 While the ratio of the2-chlorol,3butadiene to the butadionos produced by this process rangofrom robbery to oc-alkylacrylate esters can be varied within a broadrange, plastic materials. Grafted copolymers of 2chloro1,3buta 25grafted @Polymers havlng about 380% Of a 2Chl01`0 dienes with methylmethacrylate are excellent adhesives 13butad1ene and 70-20% 0f methylmethacrylate are for ptastictzed polyvinyl Cinorido v ery useful inadhesive compositions for polyvinyl chloride articles, for example inlaminating polyvinyl chloride m sheets to steel and other metals.CROSS-REFERENCE TO RELATED APPLICATION This application is acontinuation-in-part of my prior United states appiicaiion ser. No.836,376 ined June 2s, The dfawns a Plot of Specic gravity 0f a emulsion1969 now abandoned. of l part by weight of chloroprene and 1.1 parts byweight of mehylmethacrylate at 40 C. versus time from the be-BACKGROLUND OF THE INVENTION o ginning of polymerization. Two distinctstages can be ob- This invention relatos to oovoi ood useful o o p oly mors served, the dividing line corresponding to a density of apof2chlorol,3butadienes with alkyl and cycloalkyl esters proxlmately 1034(and me about 120 mmutes)' of unbranched a-(C1-C4)alkylacrylates and tomethods DETAILED DESCRIPTION OF THE INVENTION for their manufacture. Forpurposes of this disclosure chloroprene (2-chlorol,3butadiene) and2,3-dichloro-l, 40 3-butadiene are referred to generically as2-chloro-1,3 butadiene. i

It is known to copolymerize 2chlorol,3butadiene (chloroprene) with othermonomers, which include for example acrylic esters. Such copolymers arebelieved to have both the 2-chloro-l,3butadieiie units and the comonomerunits incorporated into the copolymer backbone.

It is desirable for certain applications, such as for eX- ampleadhesives, to prepare copolymers in which some polar comonomer units areincorporated into the copolymeric backbone while additional units aregrafted onto it. However, such copolymers of 2-chloi'o-l,3-butadieneswith grafted side chains were not known heretofore. The term "graftedcopolymer, as used in this application, means a copolymer in which somevunits of one of the comonomers are incorporata into the copolymecbackbone While of the specific gravity of the emulsion is a convenienttool other units of the same comonomer are grafted onto it. for Studyingoooh polymerization Stop. Thus, during Stage ,SUMMARY OF THE INVENTION Ithe density of the emulsion gradually increases with time until itreaches a plateau. It can be shown by analysis that substantially all ofthe initially present chloroprene and/or 2,3-dichloro-l,3-butadiene is,at the end of Stage I, copolymerized with a portion of the acrylate 30Drawing Two stages observed during the emulsion copolymerization of2chloro-l,3butadienes with an a-alkylacrylate ester according to thepresent process suggest a two-step reaction. In the first step, acopolymer of 2-chloro-1,3- butadiene or 2,3-dichloro-1,3-butadiene withthe acrylic 45 comonomer is believed to be formed. This step isinsensitive to the nature of the surface active agent and proceeds at afairly constant rate until substantially all the 2-chloro- 1,3-butadienehas been used up. In the second step, free acrylic comonomer grafts ontovthe copolymer backbone formed in the first step until all the acryliccomonomer is used up. This second step is very sensitive to the natureof the surface active agent used in the preparation of the emulsion.

Progress of the reaction can be followed by any suitable technique knownin the art for the study of polymerization kinetics. It has been foundthat determination According to this invention, grafted copolymers of 2-60 chloro-1,3-butadienes are obtained by emulsion copolymerization of a2-chloro-l,3butadiene with at least one comonomer of the formulacomonomer. il) Grafting is believed to take place during Stage II. Dur-0H2=CC0 R, ing this period the emulsion density increases at a fast rateuntil it eventually reaches a plateau when the -alkylacrylate estermonomer is exhausted. The overall converwhere R is an unbranched alkylradical having 1-4 carbon sion thus is virtually quantitative. atoms andR1 is an alkyl or a cycloalkyl radical having o Peferred alkyl andcycloalkyl a-alkylacrylate esters 7 1-12 carbon atoms. Such monomers arehereinafter someare methacrylates, which are inexpensive and readilytimes referred to as formula monomers for convenience. available.However, ir-ethylacrylateI esters, normal a-propylacrylate esters, andnormal a-butylacrylate esters also can be used. Representative alkyl andcycloalkyl radicals R1 in Formula I representing suitablea-alkylacrylates include methyl, ethyl, propyl, isopropyl, butyl, hexyl,nonyl, decyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. Thepreferred acrylic ester is methyl methacrylate. Mixtures of two or moreacrylic esters differing in their R or R1 groups can be used. Althoughalkyl acrylates (i.c. alkyl esters of unsubstituted acrylic acid) arenot suitable comonomers in the process of this invention, a mixture ofan acrylate and an a-alkylacrylate can be used. The reaction rate withsuch a mixture is slower than the reaction rate with an a-alkylacrylateester alone, but a quantitative yield of a graft copolymer can beobtained.

The 2-chloro-1,3butadiene can be either chloroprene(2chloro-1,3-butadiene), or 2,3-dichloro-1,3-butadiene, or a mixture ofthem. The presence of the dichloro monomer is sometimes advantageouseven when the chloroprene is the principal monomer of this class.

Although the initial ratio of chloroprene or 2,3-dichloro-1,3butadieneto the acrylic monomer can be varied quite widely, it has been foundthat a certain minimum amount of the acrylic monomer must be present inorder to obtain both copolymerization and grafting. For methylmethacrylate this minimum amount is about by Weight of the starting2-chloro-1,3butadiene and generally it is less than about The acrylicmonomer unit content of the final copolymer obtained is from l5 to 80%by weight, but except as determined by this requirement, there is noupper limit on the proportion of acrylic comonomer at the start of thepolymerization.

When small amounts of the acrylic monomer are used, the graft copolymerproduct is quite elastomeric. With methyl methacrylate as the monomer,useful adhesives for plasticized polyvinyl chloride articles areobtained within the 2-chloro-1,3-butadiene/methyl methacrylate Weightratio of about 4:1 to 1:1. As the concentration of the acrylateincreases, the resulting copolymers gradually lose their elastomericproperties and become more plastic. Rubbery grafted copolymers obtainedwith alkyl and cycloalkyl a-alkylacrylates are resistant to ozone and tochemicals and should find application in adhesives, in making molded andextruded articles, such as gaskets, and in coating electric wires.

A chain transfer agent usually is present in the polymerization medium.The purpose of this additive is to prevent formation of copolymers ofvery high molecular weight, which tend to be crosslinked and insoluble.Any mercaptan is a suitable transfer agent, but dodecyl mercaptan ispreferred because of its low volatility and consequently lack of astrong offensive odor. Higher mercaptans, such as hexadecyl andoctadecyl mercaptans, can be used instead of dodecyl mercaptan.Iodoform, a known chain transfer agent, also can be used. Certain othercompounds known in the polymer art as effective chain transfer agents,such as dialkylxanthogen disuldes, or iodine, are unsuitable becausethey extend reaction times beyond practical limits.

The reaction is carried out in the presence of a polymerizationcatalyst. Although many free-radical generating catalysts are effectivein promoting the polymerization of chloroprene, it has been found thatthe present copolymerization is most effectively promoted by a redoxsystem. Typical redox pairs which can be used in the present processinclude sodium sullite/potassium persulfate, ammonium persulfate/sodiumbisulfite, cumene hydroperoxide/sodium hydrosulte, ammonium persulfate/sodium formaldehyde sulfoxylate, t.butyl hydroperoxide/ sodiumformaldehyde sulfoxylate, and potassium persulfate/sodium metabisuliite.

The polymerization reaction is usually run at atmospheric pressure andat a temperature of about l0-60 C. Below about 10 C. the reaction ratesare somewhat too 4 slow to be practical. Above 60 C. there is a risk ofvolatilization of the 2-chloro-1,3butadiene. It is also possible to runeach reaction stage at a different temperature, maintaining atemperature of not over `60 C. during the copolymerization step andincreasing the temperature to about C. during the grafting step.

It has been found that grafting is accomplished very effectively whenthe emulsion is prepared in the presence of at least one anionic surfaceactive agent whose cation has one of the following structures:triethanolammonium, tri(2propanol)ammonium, diethanolammonium and aC1-C3 alkyldiethanolammonium. The anions of such surfactants preferablyare derived from strong acids, such as organic sulfonic acids, acidsulfate esters, and acid phosphate esters. Examples of suitable strongacids include dodecylbenzenesulfonic acid, decylbenzenesulfonic acid,monododecyl sulfate (known as lauryl acid sulfate), and acid phosphateesters of alkylphenol condensation products with ethylene oxide (forexample Triton QS-30 and Triton QS-44; Rohm & Haas Co.).

Instead of using a surface active agent containing one of the suitablecations, it is possible to use any other anionic surfactant and add oneor more suitable cations in the form of their salts with conventionalacids. These acids can be strong inorganic acids, such as for examplesulfuric, hydrochloric and phosphoric; or lower organic acids, such asacetic, propionic or butyric. It is believed that, when such atwo-component system is used, an active detergent containing one of theabove-mentioned cations is formed in situ.

The amount of active detergent which is present in the graftcopolymerization is about 0.5-10, preferably 1-5, parts by weight per100 parts of monomers. If too little detergent is present, undesirablecoagulation of copolymer can occur; if too much is present, the initialreaction rate is increased, and the viscosity of the emulsion becomestoo high for a practical operation.

The reaction is carried out in an inert atmosphere, preferably under anitrogen blanket. A 2-chloro-1,3-butadiene, an alkyl or cycloalkyla-alkylacrylate ester, and a chain transfer agent are emulsitied,usually also with the reducing agent of the redox catalyst system. Asthe initial exothermic reaction subsides, the oxidizing agent of theredox catalyst system is added gradually until the emulsion densityreaches a constant value. Alternatively, the oxidizing agent can beadded as the makeup stage, and the reducing agent can be addedportionwise as polymerization progresses. The polymer can be isolated byany known technique, for example by coagulation with methanol or withaqueous solutions of inorganic salts (such as sodium chloride) or bydrum-drying. Copolymers of suiiiciently low acrylate content that theyare rubbery may be isolated by a freeze roll.

Instead of adding all of the acrylic monomer at the beginning of thepolymerization reaction, it is possible to add part of the monomer atthe beginning land the remainder at the end of Stage I. Although thefinal composition of the copolymeric product Will be the same in bothcases, i.e. the proportions of chloroprene and of the acrylic comonorner-will not change, the distribution of grafted and copolymerized acryliccomonomer will be different. When the acrylic comonomer is added to themixture in two portions, the rst portion copolymerizes in part (untilchloroprene is completely used up) and grafts in part. The secondportion grafts but no longer compolymerizes. Consequently, a largerproportion of the comonomer is grafted in this manner than is possiblewhen all of the monomer is added at the beginning of the reaction.

Instead of adding the catalyst components at two different stages, bothof them could be added either at once or gradually at the same time. Thepreferred technique, described above, permits a good control of thereaction rate and consequently also of the reaction temperature.

These and other variations can be readily perceived by one skilled inthe art and advantageously applied by him to suit his particular needs.

Grafted copolymers prepared by the process of the present invention aresoluble in aromatic hydrocarbons; certain chlorinated hydrocarbons, suchas carbon tetrachloride and orthodichlorobenzene, but notperchloroethylene; and certain organic mixtures, such as toluene/methylacetate and acetone/hexane. They are dispersible in ketones, such asmethyl ethyl ketone and acetone, with formation of organosols. Graftedcopolymers which contain about 50-80% by Weight 2-ch1oro-1,3butadieneunits and 50-20% by weight methyl methacrylate comonomer units areuseful adhesives for plasticized polyvinyl chloride. In particular, theyare excellent vinyl-to-steel adhesives and in general vinyl-to metaladhesives. These new graft copolymers are attacked slightly or not atall by dioctyl phthalate, which is the most commonly used plasticizerfor polyvinyl chloride, and therefore are particularly suitable for suchapplications. They should be especially useful in the manufacture ofplasticized polyvinyl chloride/ steel laminates.

The invention is now illustrated by examples of certain preferredembodiments thereof. All parts, percentages, and proportions, both inthe examples and in the adhesion testing data are by weight unlessotherwise indicated.

EXAMPLE l A chloroprene-methyl methacrylate copolymer grafted withpoly(methyl methacrylate) side chains and containing an overall ratio of2 parts chloroprene to 1 part methyl methacrylate is prepared asfollows:

A mixture of 1000 grams of chloroprene, 500 vgrams of methylmethacrylate and 5.5 grams of dodecyl mercaptan is emnlsied with asolution of 42 grams of triethanola'mmonium dodecylbenzenesulfonate and4.5 grams of sodium sulfite in 1650 grams of Water and stirred with goodagitation in a flask under a nitrogen atmosphere. The temperature risesspontaneously and is maintained at approximately 40 C. throughout thepolymerization. After noticeable evolution of heat subsides, 1.0 ml. ofa 2% aqueous solution of potassium persulfate catalyst is added every 15minutes, until the specific gravity as determined by hydrometer reachesa constant value of 1.09'1. At this point, both monomers aresubstantially exhausted by the polymerization reaction. Nineteenmilliliters of the catalyst solution are required, and the totalpolymerization time is about hours. The polymer, isolated by coagulationwith methanol and drying, contains 26.3% chlorine (theory =26.6%.

EXAMPLE 2 A chloroprene-methyl methacrylate copolymer grafted withpoly(methyl methacrylate) side chains and containing an overall ratio of4 parts chloroprene to l part methyl methacrylate is prepared accordingto the procedure given in Example 1 by emulsifying 400 grams ofchloroprene, 100 grams of methyl methacrylate and 1.9 grams of dodecylmercaptan with a solution of 14 grams of triethanolammoniumdodecylbenzenesulfonate and 1.5 grams of sodium sulfite in 550 grams ofwater. The polymerization time is about 6.5 hours; the rnal specificgravity is 1.095; and the catalyst requirement (2% potassium persulfate)is 14 ml. The polymer, isolated by coagulation with methanol and drying,contains 31.4% chlorine (theory=32.0%

EXAMPLE 3 A chloroprene-methyl methacrylate copolymer grafted withpoly(methyl methacrylate) side chains and containingr an overall ratioof 1 part chloroprene to 2 parts methyl methacrylate is preparedaccording to the procedure given in Example 1 by emulsifying 334 gramsof chloroprene, 666 gra-ms of methyl methacrylate and 2 grams of dodecylmercaptan with a solution of 34 grams of triethanolammoniumdodecylbenzenesulfonate and 4 grams of EXAMPLE 4 A chloroprene-methylmethacrylate copolymer grafted with poly(methyl methacrylate) sidechains and containmg an overall ratio of 2 parts chloroprene to 1 partmethyl methacrylate is prepared by the procedure of Example 1, but usingdifferent surfactants, as shown in Table I below. The amounts ofingredients are as follows:

Grams Chloroprene 334 Methyl methacrylate 166 Dodecyl mercaptan 1.5Water 540 Surfactant (amount of active ingredient) 15 Sodium suliite 1.5

TABLE I Polymer- Catalyst 1 Final Percent ization consumpspecific Cl insurfactant time, m. tion, ml. gravity polymer (a) Triethanolammoniumdodecylbenzenesnionate 290 7 1. 091 26. 2 (b) Technicaltrlethanolammonnium iauryl sulfate 210 7 1. 091. 26. 6 (c) Technicalsodium lauryl sulfate plus trlethanolammouium Sul- 2 210 7 1.090 27.0(d) Methyldiethanolammonlum dodecylbenzenesulfonate 300 10 1. 091 26. 5(e) Tripropauolaminonlum dodecylbenzenesulfonate 300 10 1. 090 26. 6

1 2% aqueous potassium persulfate. 2 In this ease, 15 grams of sodiumsalt of lauryl acid sulfate is used plus a molar equivalent oftriethanolammonium sulfate.

EXAMPLE 5 A chloroprene-isobutyl methacrylate copolymer grafted withpoly(isobutyl methacrylate) side chains and containing a 1:1 ratio ofchloroprene to isobutyl methacrylate is prepared using the procedure ofExample 1 and the recipe below:

Grams Chloroprene 250 Isobutyl methacrylate 250 Dodecyl mercaptan 1.85Triethanolammonium dodecylbenzenesulfonate 14.0 Water 760 Sodium sulfite1.5

Two percent potassium persulfate is added in 0.5 ml. increments (8.5mls. total). The final speciiic gravity is 1.045, obtained in apolymerization time of 300 minutes. The solids content is 40.4%.

EXAMPLE I6 RECIPE Grams Chloroprene 250 Acrylic ester, cf. Table II 250Dodecyl mercaptan a- 1.85 Water 765 Triethanolammoniumdodecylbenzenesulfonate 15 Sodium suliite 1.5

Catalyst: Aqueous 2% potassium persulfate Polymerization temperature: 40C.

TAB LE II Catalyst Polym. Final Percent consumptime, specic Cl inAcrylic ester tion, ml. min. gravity polymer (a) Methyl methacrylate 8.240 1. 07 8 19. 6 (b) Ethyl methacrylate 7. 225 1. 059 19. 6 (c) Propylmethacrylate 10. 0 300 1. 053 (d) n-Butyl methacrylate 1l. 0 390 1. 04420. 8 (e) iso-Butyl methacrylate 8. 5 300 1. 045 19. S (f)2-ethylhexy1methacrylate- 10.0 300 1. 030 19. 9 (g) 50/50 methylmethacrylate n-butyl methacrylate 8. 0 240 1. 060 19. 6 (h) 50/50 methylmethacrylate n-butyl aerylate 13. 0 500 1. 057 19. 9

EXAMPLE 7 A 2,3-dichloro-1,3-butadiene-methyl methacrylate c0- polymergrafted with poly (methyl methacrylate) side chains and containing anoverall ratio of 1 part of 2,3- dichloro-l,3butadiene to 1 part ofmethyl methacrylate is prepared according to the procedure given inExample l by emulsifying 5100 grams of 2,3-dichloro-l,3-butadiene, 500grams of methyl methacrylate and 4.65 grams of dodecyl mercaptan With asolution of 50 grams of triethanolammonium dodecylbenzenesulfonate (60%solution) and 5 grams of sodium sulte in 2000 grams of water. Thepolymerization time is about 2 hours; the final specific gravity is1.078; and the catalyst requirement (2% potassium persulfate, 0.2%2-anthraquinone sodium sulfonate) is 20 to 25 ml. Chlorine content is28.3%; theoretical chlorine content is 28.83%.

The polymer is insoluble at room temperature in toluene or a mixedsolvent such as toluene/methyl ethyl ketone/hexane (1:1:1 by weight) butsoluble in hot toluene (heated on the steam bath). The cast ftlm fromthe toluene solution of this polymer shows high resistance toplasticizers (such as dioctyl phthalate).

EXAMPLE 8 A chloroprene/2,3 dichloro 1,3 butadiene/methyl methacrylateterpolymer grafted with poly (methyl methacrylate) side chains andcontaining an overall ratio of 1 part of chloroprene to 2 parts of2,3-dichloro1,3buta diene to 1 part of methyl methacrylate is preparedas follows:

A mixture of 250 grams of chloroprene, 500 grams of2,3-dichloro-l,3-butadiene, 250 grams of methyl methacrylate and 4.65grams of dodecyl mercaptan is emulsied with a solution of 50 grams oftriethanolammonium dodecylsulfonate (60% solution) and 5 grams ofsodi-um suliite in 2000 grams of water and stirred with good agitationin a flask under a nitrogen atmosphere. The temperature risesspontaneously and is maintained at approximately 40 C. throughout thepolymerization. After noticeable evolution of heat subsides, 2.0-7.0 ml.of an aqueous solution of catalysts comprising 2% of potassiumpersulfate and 0.2% of 2-anthraquinone sodium sulfonate is added everyminutes, until the specific gravity as determined by hydrometer reachesa constant value of 1.085 at /4 C. At this point, the monomers aresubstantially exhausted by the polymerization reaction. Forty-five tofty-ve milliliters of the catalyst solution are required, and the totalpolymerization time is four hours. Chlorine analysis (Schoniger ilaskmethod) is 38.7%, vs. 38.7% theoretical.

EXAMPLE 9 acrylate) side chains and containing an overall ratio of 1part chloroprene, 3 parts 2,3-dichloro-1,3-butadiene and 1 part ofmethyl methacrylate is prepared according to the procedure given inExample l by emulsifying 200 Igrams of chloroprene, 600 grams of2,3-dichloro-1,3- butadiene, 200 grams of methyl methacrylate and 4.65grams of dodecyl mercaptan with a solution of 50 grams oftriethanolammonium dodecylbenzenesulfonate (60% solution) and 5 gramssodium sulte in 2000 grams of Water. The polymerization time is aboutfour hours; the nal specific gravity is 1.089 at 20/4; and the catalystrequirement (2% potassium persulfate, 0.2% 2-anthraquinone sodiumsulfonate) is 45 to 55 ml. Chlorine analyzed 40.8% (Schoniger :askmethod) vs. 42.4%

A chloroprene/2,3 dichloro 1,3 butadiene-methyl methacrylate terpolymergrafted with poly (methyl meththeoretical.

EXAMPLE 10 A chloroprene/2,3 dichloro 1,3 butadiene/methyl methacrylateterpolymer grafted with poly (methyl methacrylate) side chains andcontaining overall ratio of 1.6 parts chloroprene to 5 parts2,3-dichloro-1,3-bu tadiene to 3.4 parts methyl methacrylate is preparedaccording to the procedure given in Example 1 Vby emulsifying 160 gramsof chloroprene, 500 grams of 2,3-dichloro-1,3-butadiene, 240 grams ofmethyl methacrylate and 4.65 grams of dodecyl mercaptan with a solutionof 50 grams of triethanolammonium dodecylbenzenesulfonate (60% solution)and 5 grams of sodium sullite in 2000 grams of Water. The polymerizationtime is 4 hours and the final gravity is 1.078 at 20/4 C.

EXAMPLE ll A chloroprene/2,3 dichloro 1,3 butadiene/butyl methacrylateterpolymer grafted with poly (butyl methacrylate) side chains andcontaining an overall ratio of 1 part chloroprene to 2 parts2,3-dichloro-1,3-butadiene to 1 part butyl methacrylate is preparedaccording to the procedure given in Example l by emulsifying 250 gramsof chloroprene, 500 grams of 2,3-dichloro-1,3-butadiene, 250 grams ofbutyl methacrylate and 4.65 grams of dodecyl mercaptan with a solutionof 50 grams of triethanolammonium dodecylbenzenesulfonate and S grams ofsodium sulte in 2000 grams of water. The polymerization time is 4 hoursand the nal gravity is 1.070 at 20/4 C. Chlorine analysis is 38.5%(Schoniger flask method )vs. 38.7% theoretical.

EXAMPLE l2 A chloroprene-methyl methacrylate copolymer grafted with poly(methyl methacrylate) side chains and containing an overall ratio of 1chloroprene/ 10.1 methyl methacrylate by weight is prepared according tothe procedure given in Example 1 by emulsifying 45 grams of chloroprene,455 grams methyl methacrylate and 1.85 grams of dodecyl mercaptan with asolution of 15 grams of triethanolammonium dodecylbenzenesulfonate and1.5 grams of sodium sulfite in 550 grams of water. The polymerizationrequires 21 ml. of catalyst 1% aqueous potassium persulfate) and iscomplete in 3 hours 45 minutes. The product is isolated by coagulationwith methanol. The dried polymer contains 3.7% chlorine (theory-:3.6%CL).

Vinyl-to-steel adhesive test procedure The following formulation iscompounded on a rubber mill at 50 C.

Parts Test polymer (as shown in Table III)2,2rnethylenebis(4-methyl-6-t-butylphenol) 2 Magnesium oxide, rubbergrade 4 Zinc oxide, rubber grade 5 The adhesive solution mix is preparedby ball milling 111 parts of the mill mix with `604 parts by weight of asolvent composed of equal volumes of methyl ethyl ketone and toluene;0.5 part Water; and 40 parts oil-soluble phenolic resin, until a smoothcement is obtained.

Two coats of the adhesive are applied to fabric-backed polyvinylchloride plastic sheet containing 48% dioctyl phthalate (based on vinylpolymer), and to cold-rolled t-butyl phenolic resin, until a smoothcement is obtained. steel which has been wiped with trichloroethylene. A

15-30 minute drying period is allowed between the two coats. Fifteen to30 minutes after applying the second coat of adhesive, thevinyl sheetis` bonded to the steel using an approximately 1-1/2'" wide steel handroller to provide bonding pressure. After aging, as indicated below, the180 peel strength is measured on a Scott tester operated at a separationrate of 2" per minute.

The average strength per linear inch (p.l.i.) of bonded surface is givenin Table III below:

TABLE III Peel strength (p.l.i.) at room temp.

Bond aging (days) at room temp. Polymer 1 1 Polymer 2 2 Polymer 3 3 1Control, outside the scope o this invention. A fast crystallizing,mercaptan-modiled chloroprene homopolymer, commercially used as aquick-setting adhesive.

2 Grafted copolymer of Example 4.

3 Control, outside the scope of this invention. A slow erystallizingcopolymer oi about 99.4 parts ehloroprene and 0.6 parts methacrylicacid.

4 Cohesive failure occurs, rather than adhesive failure.

where R is an unbranched alkyl radical having 1-4 carbon atoms, and R1is an alkyl or cycloalkyl radical having 1-12 carbon atoms, withadditional units of said for-mula monomer grafted onto the copolymerbackbone of said addition random copolymer to a total formula monomercontent in the product of 15 to 80% by weight, the ratio of graftedformula monomer to copolymerized formula monomer being from 0.76 to 39;said process consisting essentially of:

(l) in an inert atmosphere, contacting and emulsifying in water 100parts by weight of a said chloro- 'L3-butadiene with about from 17.7 to400 parts by weight of a said formula monomer or monomers in thepresence of an anion of an `anionic surface active agent together withapproximately an equivalent amount of a cation selected from the groupconsisting of triethanolammonium, tri(2 propanol) ammonium,diethanolammonium, and a C1-C3 alkyldiethanolammonium, the total amountof said anion and cation being about 0.5 to 10.0 parts per 100 parts ofmonomers, while adding a polymerization catalyst;

(2) maintaining the components in emulsion at a temperature of aboutfrom to 60 C., whereby the said formula monomer randomly copolymerizeswith the said 2-chloro 1,3 butadiene until substantially all of thelatter is exhausted to form a copolymer backbone and thereafter residualformula monomer graft-polymerizes onto said copolymer backbone, and

(3) continuing the graft copolymerization until the total formulamonomer content of the product is to 80% by weight.

2. A process of claim 1 wherein the formula monomer is methylmethacrylate.

3. A process of claim 1 wherein the formula monomer is butylmethacrylate.

l4. A process of claim 1 wherein the cation is added as a salt of aninorganic or lower carboxylic acid, and the anion is added as an anionicsurface active agent in association with some other cation.

5. A process of claim 1 wherein the specified cation and the anion areadded in association with each other in one and the same surface activeagent.

6. A process of claim 5 wherein the proportion of the surface activeagent is about 1-5 parts by weight per 100 parts of the total initialmonomer.

7. A process of claim 1 in which the monomer used as the startingmaterial with the formula monomer is 2-chloro-1,3butadiene.

8. A process of claim 1 in which the monomer used as the startingmaterial with the formula monomer is 2,3-dichloro-1,3-butadiene.

9. A process of claim 1 in which the monomer used as the startingmaterial with the formula monomer is a mixture of 2chloro-l,3butadieneand 2,3-dichloro-1,3 butadiene.

10. A lpolymeric composition of matter consisting essentially of (A) anaddition random copolymer consisting essentially of about parts 'byweight of a chloro- 1,3-butadiene selected from the group consisting of2- chloro 1,3 butadiene and 2,3-dichloro 1,3 butadiene with about from10 to 50 parts by weight of one other monomer or monomers of the formulawhere R is an unbranched alkyl radical having 1-4 carbon atoms and R1 isan alkyl or cycloalkyl radical having 1-12 carbon atoms, with (B)additional polymeric units of said formula monomer grafted onto thecopolymeric backbone of said addition random copolymer to a totalformula monomer content in the product of 15 to 80% by weight, the ratioof grafted formula monomer to copolymerized formula monomer being from0.76 to 39, said polymeric composition of matter being produced by aprocess of claim 1.

11. A composition of claim 14 in which the monomer used as the startingmaterial with the formula monomer is 2-chloro-1,3butadiene.

12. A composition of claim 14 in which the monomer used as the startingmaterial with the formula monomer is 2,3-dichloro-1,3-butadiene.

13. A composition of claim 14 in which the monomer used as the startingmaterial with the formula monomer is a mixture of 2-chloro-1,3buta\dieneand 2,3-dichloro- 1,3-butadiene.

14. In the process of bonding a plasticized polyvinyl chloride articleto steel by applying an adhesive between the polyvinyl chloride andsteel surfaces, the improvement of using as the adhesive an adhesivecomprising a composition of claim 10 in which the formula monomer ismethyl methacrylate and is present in the proportion of 20 to 70% byweight and the proportion of chloro- 1,3-butadiene is 30 to 80% byweight.

References Cited UNITED STATES PATENTS 2,404,268 7/ 1946 -Barnes 260-8633,310,544 3/1967 Alto 260--86.3 3,468,833 9/ 1969 Meincke 260-8793,471,591 10/ 1969 Lindsey 260-879 HARRY WONG, IR., Primary ExaminerU.S. Cl. X.R.

117-128.4, 132, 138.8, 161; 161--2183 26031.2 R, 32.8 R, 33.6 UA, 33.8UA, 80.81, 86.3, 879 R, 890

